是否还在使用 register 关键字?
刚刚在 C++ 中遇到 register 关键字，我想知道这似乎是个好主意(将某些变量保存在寄存器中)编译器是否会默认执行此操作?
Just came across the register keyword in C++ and I wondered as this seems a good idea (keeping certain variables in a register) surely the compiler does this by default?
所以我想知道这个关键字还在使用吗?
So I wondered is this keyword still used?
推荐答案
大多数实现只是忽略 register 关键字(除非它强加了语法或语义错误).
Most implementations just ignore the register keyword (unless it imposes a syntactical or semantical error).
该标准也没有说任何东西都必须保存在寄存器中；只是它暗示了该变量将经常使用的实现.它的使用甚至已被弃用.
The standard also doesn't say that anything must be kept in a register; merely that it's a hint to the implementation that the variable is going to be used very often. Its use is even deprecated.
3) 寄存器说明符是对实现的提示，即如此声明的变量将被大量使用.[ 注意:可以忽略提示，并且在大多数实现中，如果采用变量的地址，它将被忽略.这种用法已被弃用(见 D.2).― 尾注 ]
7.1.1 Storage class specifiers [dcl.stc]
3) A register specifier is a hint to the implementation that the variable so declared will be heavily used. [ Note: The hint can be ignored and in most implementations it will be ignored if the address of the variable is taken. This use is deprecated (see D.2). ― end note ]
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